Primary and secondary coordination of crown ethers to scandium(iii). Synthesis, properties and structures of the reaction products of ScCl3(thf)3, ScCl3·6H2O and Sc(NO3)3·5H2O with crown ethers

Autor: Michael Webster, Gillian Reid, Michael C Popham, Michael D. Brown, David C. Murray, William Levason
Rok vydání: 2003
Předmět:
Zdroj: Dalton Transactions. :857-865
ISSN: 1477-9234
1477-9226
DOI: 10.1039/b210458j
Popis: The synthesis and spectroscopic characterisation of [ScCl(15-crown-5)(MeCN)][SbCl6]2, [ScCl2(18-crown-6)][FeCl4] and [ScCl2([15]aneS2O3)][FeCl4] ([15]aneS2O3 = 1,4-dithia-7,10,13-trioxacyclopentadecane) are reported, the last containing the first example of thioether-scandium(III) coordination. The structure of [ScCl(15-crown-5)(MeCN)][SbCl6]2 reveals a pentagonal bipyramidal cation with axial Cl and MeCN, whilst [ScCl2(18-crown-6)][FeCl4] is also pentagonal bipyramidal with axial Cl ligands. 1H and 45Sc NMR spectroscopies have been used to study the speciation in the ScCl3/18-crown-6 system in the presence of the Lewis acids SbCl5 and FeCl3 in anhydrous MeCN. Hydrolysis of any of the above complexes and of [Sc(12-crown-4)2]3+ (formed from ScCl3(thf)3, crown and SbCl5), results in the formation of [ScCl3(H2O)3]·crown, the solution NMR spectra of which show a common scandium species and uncomplexed crown ether. The structure of [ScCl3(H2O)3]·18-crown-6 reveals a mer octahedral scandium species which is hydrogen bonded via the scandium-coordinated water to the 18-crown-6 (secondary coordination) leading to infinite chains. Similar complexes have been isolated directly from reaction of ScCl3·6H2O and the crown ethers in absolute ethanol, including [ScCl3(H2O)3]n·(crown) (n = 1 or 2, crown = 18-crown-6; n = 2, crown = 15-crown-5 or 12-crown-4). Hydrated scandium nitrate and the crown ethers react in ethanol solution to form a surprisingly diverse range of structural types containing the crown ethers hydrogen bonded to the scandium-aquo-nitrato or scandium-aquo-hydroxo-nitrato complexes. X-Ray crystal structures are reported for [Sc(H2O)2(NO3)3]·(12-crown-4)2, [Sc(H2O)4(NO3)2]NO3·15-crown-5 and [Sc2(NO3)2(H2O)6(OH)2](NO3)2·12-crown-4. However, in the related [Sc2(NO3)4(H2O)4(OH)2][Na(12-crown-4)2](NO3)·(H2O)3 the hydrogen bonding occurs between the lattice water and the scandium dimer unit.
Databáze: OpenAIRE
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